"Chemosignals," which are excretions that elicit a physiological or behavioral response from humans, have been previously shown to incite negative emotions. The researchers wanted to know the effects of the opposite sentiment.

They had 12 men watch movies that provoked feelings of fear or happiness in them, while a control group viewed neutral scenes. Underarm sweat samples were taken, and then 36 women were instructed to smell the pads. Kinda ew, but hold on.

The researchers then measured facial expressions after each sniff, and found that the women smiled more when they took a whiff of the perspiration of happy men, compared to the sweat of the dudes who watched the neutral clips.

"We observed that exposure to body odor collected from senders of chemosignals in a happy state induced a facial expression and perceptual-processing style indicative of happiness in the receivers of those signals," the abstract says.

Does B.O. factor into this at all? Because I can't get cheery about that. More research is needed to establish a sound conclusion on this, but take note: if your partner or friend is sweaty (and happy), then smell away.